1. Field
This application relates to a robot and a friction compensation method for the robot that enhance tracking performance between a master device and a slave device of the robot.
2. Description of Related Art
A robot is a mechanical device that automatically performs any operation or work. Robots operate using power instead of people or along with people, and may be classified into home robots, exploration robots, industrial robots, and medical robots, for example, depending on their field of use.
A medical robot may be called a surgical robot, and may be applied to various fields of medicine including surgery. The surgical robot may include a master device and a slave device that is remotely controlled by the master device.
The master device includes an input unit, and an operator may remotely control movement of the slave device by manipulating the input unit.
The slave device may include a robot arm to which a surgical instrument is coupled, and a body to which the robot arm is connected. The robot arm may include a plurality of links, and a motor may be provided at each connection portion (i.e., joint) between the links.
The motor provided at the joint may be driven to follow a speed set by the input unit of the master device. When driving the motor provided at the joint, it may be necessary to perform friction compensation to compensate for friction of each joint.
In a conventional surgical robot, to compensate for friction, a speed sensor is provided at each joint of the robot arm to measure a speed of the joint. A friction compensation value is calculated based on the measured speed of the joint. The motor performs friction compensation based on the calculated friction compensation value.
However, although a friction compensation method used in the conventional surgical robot may improve a motion of the robot arm because it compensates for friction of the joint of the robot arm based on a speed of the joint, the amount of friction compensation must be limited to ensure that movement of a slave device (or master device) more accurately tracks movement of a master device (or slave device).